Cyclic acetals as next-generation oxygenated diesel additives from lignocellulosic biomass and plastic waste

The decarbonization of heavy-duty transport, marine shipping, and aviation require sustainable liquid fuels that are compatible with existing infrastructure and derived from renewable carbon sources without competing with food or land resources. Cyclic acetals, particularly 1,3-dioxolane and 1,3-dioxane derivatives, have recently emerged as promising oxygenated fuel candidates capable of integrating multiple bio-hybrid carbon streams. These compounds can be synthesized from lignocellulose biomass-derived diols and higher aldehydes, captured CO 2 valorized with green hydrogen, and C 1 intermediates obtained from plastic waste. Compared with traditional formaldehyde-based routes, the use of higher aldehydes and catalytic CO 2 /H 2 conversion pathways helps overcome thermodynamic limitations and phase-separation challenges in acetal synthesis. Process intensification strategies, such as reactive extraction and reactive distillation in integrated catalytic columns, further enable simultaneous synthesis and purification, simplifying process design and improving scalability. Cyclic acetals exhibit favorable fuel properties, including full miscibility with conventional diesel and jet fuels, high cetane numbers, excellent cold-flow characteristics, and stable oxygenated structures resistant to corrosion and degradation during storage and combustion. These attributes make them attractive molecular platforms for advanced bio-hybrid fuels, enabling pathways toward carbon-neutral and potentially carbon-negative diesel and aviation fuels derived from biomass, CO 2 , and recycled plastics. Remaining challenges include catalyst durability, impurity tolerance, pilot-scale validation, and techno-economic feasibility.